摘要:

ABSTRACTEquilibrium data needed in modeling of osmotic dehydration are reported for unblanched diced potato in contact with aqueous solutions of sodium chloride. Diced potato, 1 cm cubes, were equilibrated with 0–12% (w/w) aqueous NaCl solutions at three temperatures (8, 21 and 35°C). the mass fraction of total solids nonsalt (wF3) in potato at equilibrium was modeled as a function of mass fraction of total solids in the fresh material at full turgor (wF3), concentration of NaCl in the external solution (wIB) and temperature. Using wF3and wIB, and assuming that the activity of NaCl in the potato tissue and the external solution at equilibrium are equal, equilibrium densities were calculated based on the principle of volume additivity. the predicted and experimentally measured equilibrium densities were in close agreeme

ISSN:0145-8876    

DOI:10.1111/j.1745-4530.1991.tb00134.x

出版商:Blackwell Publishing Ltd    

年代:1991

数据来源: WILEY

摘要:

ABSTRACTA device was developed to determine the electrical conductivities of foods under ohmic or conventional heating conditions. Orange and tomato juices (serum and various solids contents) were tested in the device. the electrical conductivity of juices increased with temperature and decreased with solids content. the temperature dependence of conductivity was linear, both under conventional and ohmic heating. Experiments on suspensions of carrot juice solids, and polystyrene spheres in sodium phosphate solution showed an increase in electrical conductivity of the suspension with decreasing particle size.

ISSN:0145-8876    

DOI:10.1111/j.1745-4530.1991.tb00135.x

出版商:Blackwell Publishing Ltd    

年代:1991

数据来源: WILEY

摘要:

ABSTRACTThe effect of rice varietal characteristics, namely, length (L): breadth (B), ratio, amylose and protein contents and processing conditions namely, extent/degree of hydrothermal treatment, degree of milling and percentage of salt addition to rice, on puffing quality were studied in detail. the L:B ratio of varieties tested showed a positive correlation (r = 0.69) with expansion ratio (ER) of puffed rice produced. Total amylose and hot water insoluble amylose contents revealed a definite pattern of relationship, with ER showing predicted peaks at 28.5% total amylose (db) and 13.5% insoluble amylose (db) for highest ER. Protein content showed a negative relationship (r =−0.79) with ER. A new method for determining extent/degree of starch gelatinization, based on Brabender hot paste peak viscosity value (viscosity of 15% slurry retained at 95°C for 20 min.) was used in this study. Normal parboiled and pressure parboiled rice having 425 BU and 240 BU peak viscosities produced highest ER of 7.5 and 9.7% respectively. A 6% milling (minimum) and a 2% salt (NaCl/CaCl2) addition during preconditioning of rice resulted in maximum

ISSN:0145-8876    

DOI:10.1111/j.1745-4530.1991.tb00136.x

出版商:Blackwell Publishing Ltd    

年代:1991

数据来源: WILEY

摘要:

ABSTRACTPineapple juice samples were ultrafiltrated using a polysulfone 10,000 molecular weight cut‐off (MWCO) membrane. However, to facilitate operations, the ultrafiltration experiments were preceeded by fractionation of juice samples using sequentially Microfiltration/Diafiltration and Ultrafiltration/Diafiltration with 8 μm; 0.4 μm; 0.2 μm and 0.1 μm membranes, using three specific experimental procedures. the 10,000 MWCO membrane was cleansed using a 40°C IN NaOH solution for a minimum of 30 min, to restore optimal membrane water permeation flux. the effects of selective fractionation processes, pretreatments (using antifoaming agent, hemicellulase, and ammonium sulfate saturation), on permeation rates, concentration levels, protein rejection and protein yields were determined. Water permeation fluxes, measured before and after each UF operation showed a dramatic flux drop from 313 L/hm2to 91 L/hm2within seven successive 10,000 MWCO membrane experiments. This occurred inspite of suitable membrane washing conditions, pretreatments and selective fractionation processing of samples. the modification, mainly due to fouling, of the integrity of the 10,000 MWCO membrane relative to concentration level was invest

ISSN:0145-8876    

DOI:10.1111/j.1745-4530.1991.tb00137.x

出版商:Blackwell Publishing Ltd    

年代:1991

数据来源: WILEY

摘要:

ABSTRACTRecovery and concentration of flavor compounds from an apple essence (x 500) was attempted by pervaporation using a silicone rubber (polydimethylsiloxane) membrane at room temperature. the flavor components were identified by GC‐MS method, and the ratio of concentration of the flavor compound in the permeate to that in the feed was determined for each component. It was found that pervaporation is indeed an effective measure for the above purpose. Concentration ratios above 20 were achieved for flavor components with boiling points lower than 100

ISSN:0145-8876    

DOI:10.1111/j.1745-4530.1991.tb00138.x

出版商:Blackwell Publishing Ltd    

年代:1991

数据来源: WILEY

摘要:

ABSTRACTA nondestructive method to measure the internal moisture distribution and to determine the effective moisture diffusion coefficient for a potato during drying and absorption was developed using NMR imaging and numerical modeling techniques. the coefficients obtained were 1.04 to 7.28 × 10−10m2/s, for moisture contents between 40% and 55% (wb), during drying with a sample temperature of 40°C; and were 9.78 × 10−12to 2.33 × 10−11m2/s, for moisture contents between 56% and 60%, during absorptio

ISSN:0145-8876    

DOI:10.1111/j.1745-4530.1991.tb00139.x

出版商:Blackwell Publishing Ltd    

年代:1991

数据来源: WILEY